Fwd: eddy current brake

[tom cloud]

>It's my understanding that the dynamic range, 20:1, is difficult for a
>simple PLL.  I think the confuser would have to adjust the feedback based on
>the current RPM range to keep it locked.  me
>

Lessee, 600 at idle to 6000 is 10:1, which is enough for me.  With a 4-star
crank sensor, you get a pulse every 45 degrees, since 2 revs = 360, right?
Then, if you PLL'd the freq by 45, you'd have 1 degree pulses, by 90,
.5 degree.  Am I right?  I think I understand the need for 'reasonable'
accuracy with firing, but you've already got a hardware (crank) 45 degree
reference.  The PLL jitter shouldn't give but only a few tenths of a degree
error, if that much.  Capture shouldn't be a problem, as I don't see how you
can rev or decelerate the engine fast enough to lose lock.

Remember, I'm just positing here -- never actually tried this.


Tom Cloud <cloud at peaches.ph.utexas.edu>